Browsing by Author "East African Agriculture and Forestry Research Organisation, Kikuyu, Kenya"
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Item Effects of Organic Mulch on Fertility of a Latosolic Coffee Soil in Kenya(1965) Robinson, J.B.D.; Hosegood, P.H.; East African Agriculture and Forestry Research Organisation, Kikuyu, KenyaMeasurements are reported on the influence of mulch on the chemical and physical characteristics of the soil and the chemical composition of the crop together with growth measurement on an indicator crop in the greenhouse and on mature coffee in the field. Mulch reduced soil acidity; increased organic carbon, Kjeldahl nitrogen, exchangeable potassium and available phosphorus and decreased exchangeable calcium and manganese. It increased total pore space, free-draining pore space and rate of rainfall acceptance in the top soil. Effects on the coffee were to increase phosphorus, potassium and in some cases nitrogen in the leaf, but reduce magnesium and calcium levels. Potassium and calcium levels were increased in feeder roots, Whereas in the ripe cherry the phosphorus level was increased but nitrogen, calcium and magnesium levels were reduced. The soil effects were reflected in increased growth of the indicator crop and mulch improved the growth of the coffee tree in a year of seasonal drought.Item Phosphorus Transformations During Plant Decomposition(1961) Birch, H.F. ; East African Agriculture and Forestry Research Organisation, Kikuyu, KenyaDuring decomposition, microbial organic P is rapidly formed from plant inorganic P. With young plant material, much of the microbial P is dephos-phorylated and becomes inorganic P. With mature material little organic P occurs even after three months' decomposition. This is associated with a less decomposable substrate and with the maintenance of a viable population. Plants generally contain sufficient inorganic P for bacterial requirements during decomposition. During dephosphory-lation of microbial organic P, acid-labile forms are first involved and then the acid-stable forms. Secondary decomposition possibly involving dead micro-organisms results in the resynthesis of both forms; these suffer further dephosphorylation and the residual products consist roughly of 70%3 acid-labile and 30 % acid-stable P. With mature material the amount of organic P remains fairly constant during five weeks' decomposition and consists of equal parts of both forms. Enzyme systems converting acid-stable and acid-labile forms to inorganic P, and acid-stable to acid-labile forms, could be distinguished. -From author's summary.
